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new 91e3acf [FLINK-25818][Docs][Kafka] Add explanation how Kafka Source
deals with idleness when parallelism is higher then the number of partitions
91e3acf is described below
commit 91e3acf7e9ce66e9faaa2d55b3a78e3b76f49374
Author: martijnvisser <[email protected]>
AuthorDate: Wed Jan 26 10:51:47 2022 +0100
[FLINK-25818][Docs][Kafka] Add explanation how Kafka Source deals with
idleness when parallelism is higher then the number of partitions
---
docs/content.zh/docs/connectors/datastream/kafka.md | 8 ++++++++
docs/content/docs/connectors/datastream/kafka.md | 9 +++++++++
2 files changed, 17 insertions(+)
diff --git a/docs/content.zh/docs/connectors/datastream/kafka.md
b/docs/content.zh/docs/connectors/datastream/kafka.md
index 048fb97..50cc2ee 100644
--- a/docs/content.zh/docs/connectors/datastream/kafka.md
+++ b/docs/content.zh/docs/connectors/datastream/kafka.md
@@ -346,6 +346,14 @@ Flink Kafka Producer 被称为 `FlinkKafkaProducer`。它允许将消息流写
```java
DataStream<String> stream = ...;
+### 空闲
+如果并行度高于分区数，Kafka Source
不会自动进入空闲状态。您将需要降低并行度或向水印策略添加空闲超时。如果在这段时间内没有记录在流的分区中流动，则该分区被视为“空闲”并且不会阻止下游操作符中水印的进度。
+[这篇文档]({{< ref "docs/dev/datastream/event-time/generating_watermarks.md"
>}}#dealing-with-idle-sources) 描述了有关如何定义 ```WatermarkStrategy#withIdleness```
的详细信息.
+
+### 消费位点提交
+Kafka source 在 checkpoint **完成**时提交当前的消费位点 ，以保证 Flink 的 checkpoint 状态和 Kafka
broker 上的提交位点一致。如果未开启
+checkpoint，Kafka source 依赖于 Kafka consumer 内部的位点定时自动提交逻辑，自动提交功能由
```enable.auto.commit``` 和
+```auto.commit.interval.ms``` 两个 Kafka consumer 配置项进行配置。
Properties properties = new Properties();
properties.setProperty("bootstrap.servers", "localhost:9092");
diff --git a/docs/content/docs/connectors/datastream/kafka.md
b/docs/content/docs/connectors/datastream/kafka.md
index fe30196..0960f6a 100644
--- a/docs/content/docs/connectors/datastream/kafka.md
+++ b/docs/content/docs/connectors/datastream/kafka.md
@@ -201,6 +201,15 @@ env.fromSource(kafkaSource, new CustomWatermarkStrategy(),
"Kafka Source With Cu
[This documentation]({{< ref
"docs/dev/datastream/event-time/generating_watermarks.md" >}}) describes
details about how to define a ```WatermarkStrategy```.
+### Idleness
+The Kafka Source does not go automatically in an idle state if the parallelism
is higher than the
+number of partitions. You will either need to lower the parallelism or add an
idle timeout to the
+watermark strategy. If no records flow in a partition of a stream for that
amount of time, then that
+partition is considered "idle" and will not hold back the progress of
watermarks in downstream operators.
+
+[This documentation]({{< ref
"docs/dev/datastream/event-time/generating_watermarks.md"
>}}#dealing-with-idle-sources)
+describes details about how to define a ```WatermarkStrategy#withIdleness```.
+
### Consumer Offset Committing
Kafka source commits the current consuming offset when checkpoints are
**completed**, for
ensuring the consistency between Flink's checkpoint state and committed
offsets on Kafka brokers.
